15. Lami's theroem states that

A. three forces acting at a point are always in equilibrium

B. if three forces acting on a point can be represented in magnitude and direction by the sides of a triangle, the point will be in the state of equilibrium

C. three coplaner forces acting at a point will be in equilibrium, if each force is proportional to the sine of the angle between the other two

D. three coplaner forces acting at a point will be in equilibrium if each force is inversely proportional to the sine of the angle between the other two

16. Principle of Transmissibility of Forces states that, when a force acts upon a body, its effect is

A. maximum if it acts at the centre of gravity of the body

B. different at different points on its line of action

C. same at every point on its line of action

D. minimum if it acts at the C.G. of the body

17. According to Law of Triangle of Forces

A. three forces acting at a point, can be represented by the sides of a triangle, each side being in proportion to the force

B. three forces acting along the sides of a triangle are always in equilibrium

C. if three forces acting on a point can be represented in magnitude and direction, by the sides of a triangle taken in order, these will be in equilibrium

D. if the forces acting on a particle be represented in magnitude and direction by the two sides of a triangle taken in order, their resultant will be represented in magnitude and direction by the third side of the triangle, taken in opposite order.

18. The Law of Polygon of Forces states that

A. if a polygen representing the forces acting at point in a body is closed, the forces are in equilibrium

B. if forces acting on a point can be epresented in magnitde and direction by the sides of a polygon taken in order, then the resultant of the forces will be represented in magnitude and direction by the closing side of the polygon

C. if forces acting on a point can be represented in magnitude and direction by the sides of a polygon taken in order, their resultant will be represented in magnitude and direction by the closing side of the polygon taken in opposite order

D. if forces acting on a point can be represented in magnitude and direction by the sides of a polygon in order, the forces are in equilibrium

19. Effect of a force on a body depends upon its

A. direction

B. magnitude

C. position

D. all the above.

20. If two forces each equal to T in magnitude act at right angles, their effect may be neutralised by a third force acting along their bisector in opposite direction whose magnitude will be

A. 2 T

B. 1/2 T

C. '1T

D. 3T

21. If a body is acted upon by a number of coplaner non-concurrent forces, it may

A. rotate about itself without moving

B. move in any one direction

C. move in any one direction rotating about itself

D. all the above.

Page **3** of **34**